Tag Archives: challenge

Dynamic programming in Haskell: automatic memoization

Posted on June 6, 2023 by Brent

This is part 2 of a promised multi-part series on dynamic programming in Haskell. As a reminder, we’re using Zapis as a sample problem. In this problem, we are given a sequence of opening and closing brackets (parens, square brackets, … Continue reading →

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Dynamic programming in Haskell: lazy immutable arrays

Posted on June 2, 2023 by Brent

This is part 1 of a promised multi-part series on dynamic programming in Haskell. As a reminder, we’re using Zapis as a sample problem. In this problem, we are given a sequence of opening and closing brackets (parens, square brackets, … Continue reading →

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Competitive programming in Haskell: introduction to dynamic programming

Posted on May 31, 2023 by Brent

In my previous post, I challenged you to solve Zapis. In this problem, we are given a sequence of opening and closing brackets (parens, square brackets, and curly braces) with question marks, and have to compute the number of different … Continue reading →

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Competitive programming in Haskell: parsing with an NFA

Posted on May 24, 2023 by Brent

In my previous post, I challenged you to solve Chemist’s Vows. In this problem, we have to decide which words can be made by concatenating atomic element symbols. So this is another parsing problem; but unlike the previous problem, element … Continue reading →

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Competitive programming in Haskell: tries

Posted on May 3, 2023 by Brent

In my previous post, I challenged you to solve Alien Math, which is about reading numbers in some base , but with a twist. We are given a list of strings representing the names of the digits through , and … Continue reading →

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Competitive programming in Haskell: topsort via laziness

Posted on April 11, 2023 by Brent

In my previous post, I challenged you to solve Letter Optimiztion. In this problem, we have a directed acyclic graph where each vertex represents a person, and there is an edge p -> q when person p sends their finished … Continue reading →

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Competitive programming in Haskell challenge: Letter Optimization

Posted on March 11, 2023 by Brent

Now that I’ve wrapped up my series of posts on Infinite 2D Array (challenge, part 1, part 2, part 3), I’d like to tackle another topic related to competitive programming in Haskell. I won’t tell you what the topic is … Continue reading →

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Competitive programming in Haskell: folding challenge

Posted on February 23, 2021 by Brent

As of this writing, I am the only person who has solved Origami on Open Kattis (see the problem statistics here). This is a shame since it is a very nice problem! Of course, I solved it in Haskell. I … Continue reading →

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Data structure challenge: application

Posted on April 6, 2020 by Brent

I forgot to mention this in my previous post, but the thing which got me thinking about the predecessor problem in the first place was this competitive programming problem on Open Kattis: Profitable Pizzas I challenge you to go and … Continue reading →

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Data structure challenge: solutions

Posted on April 6, 2020 by Brent

In my previous post I challenged you to find a way to keep track of a sequence of slots in such a way that we can quickly (in or better) either mark any empty slot as full, or find the … Continue reading →

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